1. Field of the Invention
The invention relates to biodegradable two-cycle oil compositions comprising a tridecyl oxo alcohol adipate as a biodegradable base oil, dispersant, and a lubricity agent.
2. Description of Related Art
Two-cycle engines are lubricated by mixing the lubricant with the fuel for the engine. The mixture of fuel and lubricant passes through the crankcase of a two-cycle engine, where it lubricates the moving parts in the lower portion of the engine and then flows through intake ports into the combustion chamber. There it lubricates the cylinder zone of the engine and is burned. The combustion products are vented from the combustion chambers through exhaust ports. As a consequence, a satisfactory lubricant for a two-cycle engine must not only provide adequate lubrication for moving engine parts but also must be able to pass into the combustion chamber leaving no objectionable deposits in the intake ports; must burn cleanly to avoid fouling the combustion chamber and spark plug with undesirable deposits; control varnish and sludge formation which leads to ring sticking and in turn to failure of the sealing function of piston rings; must not result in plugging of the exhaust ports and most importantly biodegrade to natural materials upon contact with the environment.
Various methods and compositions have been suggested for obtaining dispersant or biodegradable benefits for lubricating oils.
For example, U.S. Pat. No. 5,221,491 discloses controlling gel formation in two-cycle oil with an additive comprising a reaction product of a monocarboxylic acid, a polyalkylene polyamine, and a high molecular weight acylating agent. The application further disclosed additive compositions also containing a polyolefin and a pour point depressant type flow improver.
EP-A-0552554A1 discloses automotive crankcase lubricating oil compositions which have a major proportion of a biodegradable base fluid that is a blend of (a) at least one ester of isotridecyl alcohol alcohol and a mono-, di or polycarboxylic acid and (b) at least one hydrocarbon oil which has no more than 10% on a weight basis of aromatic hydrocarbons, the rest being aliphatic. The portion of (a) in the blend is disclosed to be in the range from 25 to 55% on a weight basis. This reference does not disclose two-cycle oils because it uses several ash-forming components which are unsuitable for two-cycle oil formulations.
EP-A-0259809A2 discloses a lubricating oil composition comprising 9 to 60% by weight of mineral oil and 3 to 40% by weight of polyester. The mineral oil is disclosed to have a viscosity at 100.degree. C. of 2 to 50 centistokes, a pour point of -5.degree. to -30.degree. C. and a viscosity index of not less than 80.
However, the composition of this invention provides a level of cleanliness in water cooled two-cycle engines that is surprisingly better and more environmentally friendly than that hereto obtained using commercially available composition.